.container{
    width: 100%;
    height: calc(100% - 50px);

    display: flex;
    align-items: center;
    justify-content: center;
}
#screen{
    text-align: center;
    line-height: 100px;

    width: 400px;
    height: 200px;
    font-size: 20px;
    background-color: gray;
    color: white;
    /* 圆角大小 */
    border-radius: 10px;
}
#submit{
    text-align: center;
    width: 400px;
    height: 50px;
    align-items: center;
    font-size: 20px;
    background-color: orange;
    color: white;
    /* 去掉边框线 */
    outline: none;
    border: none;
    /* 设置行高 */
    line-height: 50px;
    /* 圆角大小 */
    border-radius: 10px;
    /* 向上的边距 */
    margin-top: 20px;
    
}
#submit:active{
    background-color: aliceblue;
}